1. Field of the Invention
The present invention relates to an exposure apparatus for applying exposure light to an object to be exposed held on a stage through a photomask and forming a predetermined pattern by exposure, in particular, to an exposure apparatus for exposing an image of non-periodic pattern on a large area object to be exposed with high resolving power.
2. Description of Related Art
A conventional exposure apparatus is an exposure apparatus which intermittently irradiates exposure light to an object to be exposed conveyed at a constant speed through a photomask and exposes an image of a mask pattern of the photomask at a predetermined position. The conventional exposure apparatus includes a first imaging device arranged to capture an image of an exposure position by the photomask or a position upstream of the exposure position in a conveying direction of the object to be exposed and the first imaging device having a plurality of light receiving elements arranged in a direction substantially perpendicular to the conveying direction, a second imaging device arranged to capture an image of the exposure position by the photomask or a position upstream of the exposure position in a conveying direction of the object to be exposed and the second imaging device having a plurality of light receiving elements arranged in substantially parallel with the conveying direction, an alignment device which relatively moves the object to be exposed and the photomask in a direction substantially perpendicular to the conveying direction to correct the exposure position by the photomask, and a control device which controls drive of the alignment device on the basis of a first reference position for correcting the exposure position provided on the object to be exposed in advance when the first reference position is detected by the first imaging device and controls irradiation timing of exposure light on the basis of a second reference position for extracting the irradiation timing of exposure light provided on the object to be exposed in advance when the second reference position is detected by the second imaging device (for example, refer to Japanese Laid-Open Patent Application No. 2008-76709).
However, in the conventional exposure apparatus as described above, although a periodic pattern is easily exposed to the object to be exposed (substrate) by only controlling the irradiation timing of exposure light at a predetermined cycle while conveying the substrate in one direction at a constant speed, it is difficult to perform exposure of non-periodic pattern. Furthermore, in the conventional exposure apparatus, the photomask and the substrate are allowed to be disposed proximately to each other, and then, an image of a pattern formed on the photomask is exposed onto the substrate. Thus, an image of pattern on the substrate is blurred and resolution is deteriorated due to the presence of a collimation half angle in light from a light source irradiated to the photomask, so that there is a possibility that a fine pattern may not be formed by exposure.
Although such a problem can be solved by using a stepper exposure apparatus which performs exposure by projecting a reduced image of a mask pattern of the photomask onto the substrate by an imaging lens, when exposure is performed on a large area substrate of 1 m by 1 m, for example, there is a problem that the diameter of the lens to be used becomes large and expensive according to the size of the substrate.